Addressing the nation from the White House on Tuesday, the POTUS said the "people of Moore should know that their country will remain on the ground, there for them, beside them as long as it takes."

"As a nation, our full focus right now is on the urgent work of rescue, and the hard work of recovery and rebuilding that lies ahead," he said. "Oklahoma needs to get everything that it needs right away."

At least 120 people, including many children, were injured in what Obama called "one of the most destructive tornadoes in history." Seven children were also killed at Plaza Towers Elementary school in Moore when the tornado struck Monday afternoon.

"There are empty spaces where there used to be living rooms and bedroom and classrooms, and in time we will need to refill those spaces with laughter, community," Obama promised before adding. "We don't yet know the full extent of the damage."

On Monday night, President Obama signed a disaster declaration for Oklahoma, allowing federal aid to supplement state and local recovery efforts.

"For all those who've been affected, we recognize that you face a long road ahead," he said. "In some cases, there will be enormous grief that has to be absorbed. But you will not travel that path alone. Your country will travel it with you fueled by our faith in the Almighty and our faith in one another. So our prayers are with the people of Oklahoma today. And we will back up those prayers with deeds for as long as it takes."

Queen Elizabeth II and Pope Francis have also expressed their condolences following the horrific tragedy. In a statement issued by Buckingham Palace, the British monarch said, "I was deeply saddened to hear of the loss of life and devastation caused by yesterday's tornado in Oklahoma."

Pope Francis took to his official Twitter account to share his thoughts: "I am close to the families of all who died in the Oklahoma tornado, especially those who lost young children. Join me in praying for them," he posted Tuesday.

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